Windows desktop is usually cluttered all the time and it is very difficult to keep track of windows if you've opened too many. In Ubuntu there is a concept of workspaces, you can open as many windows and programs as you want and drag/drop them into workspaces. But unfortunately Windows does not come with such a capability.
I tried out a lot of free and sharewares but all of them had problems. Like most of them were really heavy on the CPU and memory and were really buggy. Most of them had to be integrated into Windows Explorer which caused it to crash frequently.

Now lets go into the details. You can open up to 20 virtual desktops with Dexpot. It supports 'easy to use' keyboard shortcuts with which you can switch desktops or move windows between different desktops very quickly. The shortcuts are fully customizable. So now you can open as many windows as you want, and move them to different desktops as you open new ones. And all this can be done without cluttering your desktop.